Drug-Disease Interactions — MCQs
The choice of antihypertensive medication also depends upon the co-morbid illness of the patient, and all of the following recommendations have been made except:
Which of the following agents requires the MOST caution when combined with spironolactone due to increased risk of hyperkalemia:
All of the following drugs require dose reduction in renal failure except?
A patient presents with nephrotic syndrome and hypoalbuminemia. Protein binding of which drug is not affected?
A patient on warfarin has a high INR. Which drug likely caused this?
Which of the following is the most appropriate initial antihypertensive treatment for an elderly patient with isolated systolic hypertension?
Assertion: ACE inhibitors are contraindicated in bilateral renal artery stenosis. Reason: They cause acute kidney injury by reducing efferent arteriolar tone.
Beta2-agonists cause all except:
Which of the following is not an adverse effect of chronic amiodarone therapy?
A 65-year-old woman with Parkinson’s disease has been experiencing worsening tremors despite taking levodopa. Which medication can be added to her treatment regimen?
Drug-Disease Interactions Indian Medical PG Practice Questions and MCQs
Question 1: The choice of antihypertensive medication also depends upon the co-morbid illness of the patient, and all of the following recommendations have been made except:
- A. In hypertensive patients with gout, diuretics are the first-line treatment. (Correct Answer)
- B. In hypertensive patients with heart failure, ACE inhibitors may be preferred
- C. In hypertensive patients with migraine, beta blockers are an excellent choice
- D. In hypertensive patients with peripheral vascular disease, calcium channel blockers are recommended
Explanation: ***In hypertensive patients with gout, diuretics are the first-line treatment.*** * This statement is incorrect because **diuretics**, particularly **thiazide diuretics**, can **elevate uric acid levels** and precipitate or worsen gout attacks. * Therefore, they are generally **contraindicated or used with caution** in patients with gout, not recommended as first-line treatment. *In hypertensive patients with heart failure, ACE inhibitors may be preferred* * **ACE inhibitors** are a cornerstone of heart failure treatment due to their ability to **improve cardiac remodeling**, reduce mortality, and alleviate symptoms. * They are often preferred for their **vasodilatory effects** and ability to prevent volume overload, which benefits patients with heart failure. *In hypertensive patients with migraine, beta blockers are an excellent choice* * **Beta-blockers**, such as propranolol, are effective in both **blood pressure control** and the **prophylaxis of migraines** [1]. * This makes them an excellent choice for a hypertensive patient who also suffers from migraines, offering a dual therapeutic benefit [1]. *In hypertensive patients with peripheral vascular disease, calcium channel blockers are recommended* * **Calcium channel blockers (CCBs)**, especially dihydropyridines like amlodipine, are beneficial in peripheral vascular disease (PVD) due to their **vasodilatory effects**. * They can **improve blood flow** to the extremities, which is crucial in PVD, without negatively impacting symptoms like claudication.
Question 2: Which of the following agents requires the MOST caution when combined with spironolactone due to increased risk of hyperkalemia:
- A. ACE inhibitors (Correct Answer)
- B. Beta-blockers
- C. Amlodipine
- D. Chlorothiazide
Explanation: ***ACE inhibitors*** - Spironolactone is a **potassium-sparing diuretic** that increases potassium levels by blocking aldosterone's effects in the collecting duct [1]. - **ACE inhibitors** also decrease aldosterone production [2], leading to reduced potassium excretion and a significant risk of **severe hyperkalemia** when combined with spironolactone [1, 2].*Beta-blockers* - While beta-blockers can cause a slight increase in plasma potassium by inhibiting cellular potassium uptake, this effect is generally modest and does not pose a major hyperkalemia risk when co-administered with spironolactone. - Their primary interaction concerns blood pressure and heart rate, not direct potassium handling.*Amlodipine* - Amlodipine is a **calcium channel blocker** that primarily causes vasodilation and does not significantly alter potassium balance. - Therefore, it does not substantially increase the risk of hyperkalemia when used concurrently with spironolactone.*Chlorothiazide* - Chlorothiazide is a **thiazide diuretic** that promotes potassium excretion, leading to a risk of hypokalemia. - When combined with spironolactone, a potassium-sparing diuretic, these agents can **partially offset each other's effects** on potassium balance, potentially reducing the risk of hyperkalemia compared to ACE inhibitors.
Question 3: All of the following drugs require dose reduction in renal failure except?
- A. Doxycycline (Correct Answer)
- B. Vancomycin
- C. Gentamicin
- D. Acyclovir
Explanation: ***Doxycycline*** - **Doxycycline** is primarily eliminated via the gastrointestinal tract (fecal excretion) and does NOT require dose adjustment in patients with **renal impairment**. [1] - Its unique elimination pathway makes it a safe choice for treating infections in patients with **renal failure**. - This is a key distinguishing feature among tetracyclines. *Vancomycin* - **Vancomycin** is predominantly eliminated by the kidneys (80-90% unchanged in urine). - Accumulation in renal failure can lead to **ototoxicity** and **nephrotoxicity**. - Dosage must be carefully adjusted based on **creatinine clearance** and therapeutic drug monitoring is essential. *Gentamicin* - **Gentamicin**, an aminoglycoside, is almost entirely excreted unchanged by the kidneys. - Highly **nephrotoxic** and **ototoxic** with narrow therapeutic index. - Dose reduction and extended dosing intervals are critical in **renal failure** to prevent drug accumulation and serious adverse effects. [3] *Acyclovir* - **Acyclovir** is primarily eliminated renally (60-90% excreted unchanged in urine). - Requires significant **dose reduction in renal impairment** to prevent crystalluria and neurotoxicity. [2] - Dosing adjustment based on creatinine clearance is mandatory to avoid adverse effects.
Question 4: A patient presents with nephrotic syndrome and hypoalbuminemia. Protein binding of which drug is not affected?
- A. Valproate
- B. Morphine (Correct Answer)
- C. Diazepam
- D. Tolbutamide
Explanation: ***Morphine*** - Morphine is a **low protein-bound drug** (<35%), meaning a significant portion circulates freely. - Therefore, even with **reduced albumin levels** in nephrotic syndrome, the free fraction available for action is not significantly altered. *Valproate* - Valproate is **highly protein-bound** (90-95%), primarily to albumin. - In conditions like nephrotic syndrome with **hypoalbuminemia**, a decreased binding capacity leads to a higher free drug fraction and increased pharmacological effect. *Diazepam* - Diazepam is also **highly protein-bound** (98%), mainly to albumin. - Like other highly bound drugs, **hypoalbuminemia** in nephrotic syndrome would increase its free fraction, potentially leading to increased side effects. *Tolbutamide* - Tolbutamide is another drug with **high protein binding** (>90%), predominantly to albumin. - Reduced albumin levels in nephrotic syndrome would result in a **higher free concentration** of tolbutamide, increasing its hypoglycemic effect and risk of adverse reactions.
Question 5: A patient on warfarin has a high INR. Which drug likely caused this?
- A. Amiodarone (Correct Answer)
- B. Phenytoin
- C. Carbamazepine
- D. Rifampicin
Explanation: ***Amiodarone*** - Amiodarone is a well-known inhibitor of **CYP2C9**, the primary enzyme responsible for the metabolism of **S-warfarin**, the more potent enantiomer of warfarin. - Inhibition of warfarin metabolism leads to increased warfarin levels, thereby enhancing its anticoagulant effect and causing a **higher INR**. *Phenytoin* - Phenytoin is an **enzyme inducer**, primarily of **CYP2C9** and **CYP3A4**. - Its interaction with warfarin typically leads to **decreased warfarin levels** and a **lower INR**, reducing the anticoagulant effect. *Carbamazepine* - Carbamazepine is a potent **enzyme inducer**, particularly of **CYP3A4** and **CYP2C9**. - Like phenytoin, it generally leads to **increased warfarin metabolism** and a **reduced INR**, thereby decreasing its anticoagulant efficacy. *Rifampicin* - Rifampicin is a strong **inducer of hepatic cytochrome P450 enzymes**, especially **CYP3A4** and **CYP2C9**. - Its co-administration with warfarin significantly **increases warfarin metabolism**, resulting in **lower warfarin concentrations** and a **decreased INR**.
Question 6: Which of the following is the most appropriate initial antihypertensive treatment for an elderly patient with isolated systolic hypertension?
- A. Amlodipine (Correct Answer)
- B. Lisinopril
- C. Atenolol
- D. Losartan
Explanation: Amlodipine - **Calcium channel blockers (CCBs)**, especially dihydropyridines like amlodipine, are recommended as initial therapy for isolated systolic hypertension in the elderly due to their effectiveness in reducing elevated systolic pressure [2]. - They are well-tolerated and can reduce the risk of cardiovascular events in this population. *Lisinopril* - **ACE inhibitors** like lisinopril are effective antihypertensives but are generally not the first-line choice for isolated systolic hypertension, particularly in elderly patients where a decrease in diastolic pressure might be detrimental [1]. - They are associated with side effects such as **cough** and can cause **acute kidney injury**, which can be a concern in older adults [1]. Atenolol - **Beta-blockers** like atenolol are generally not recommended as first-line therapy for isolated systolic hypertension due to their limited efficacy in lowering systolic blood pressure compared to other drug classes. - They may also worsen certain conditions common in the elderly, such as **peripheral vascular disease** and **bronchospastic lung disease**. *Losartan* - **Angiotensin receptor blockers (ARBs)** like losartan are effective for hypertension but are not typically favored over CCBs or thiazide diuretics as initial monotherapy for isolated systolic hypertension in the elderly [1]. - They share similar side effects and contraindications with ACE inhibitors, including the risk of **renal dysfunction** [1].
Question 7: Assertion: ACE inhibitors are contraindicated in bilateral renal artery stenosis. Reason: They cause acute kidney injury by reducing efferent arteriolar tone.
- A. A true R false
- B. Both A & R true, R explains A (Correct Answer)
- C. Both A & R true, R doesn't explain A
- D. A false R true
Explanation: ***Correct: Both A & R true, R explains A*** - **Assertion is TRUE**: ACE inhibitors are absolutely contraindicated in bilateral renal artery stenosis due to risk of acute kidney injury - **Reason is TRUE**: In bilateral renal artery stenosis, the kidneys depend on **angiotensin II** to maintain GFR by constricting the efferent arteriole - **R explains A**: ACE inhibitors block angiotensin II production → **efferent arteriolar dilation** → drastically reduced GFR → **acute kidney injury (AKI)** - This direct mechanistic link makes the reason a complete explanation of the assertion *Incorrect: A true R false* - While the assertion is true, the reason is also **true** (not false) - ACE inhibitors do reduce efferent arteriolar tone by blocking angiotensin II - This is the precise mechanism causing AKI in these patients *Incorrect: Both A & R true, R doesn't explain A* - Both statements are indeed true, but this option is incorrect because the reason **does explain** the assertion - The mechanism (reduced efferent arteriolar tone → decreased GFR) directly explains why ACE inhibitors are contraindicated - The causal relationship is clear and direct *Incorrect: A false R true* - The assertion is **true**, not false - ACE inhibitors are definitively contraindicated in bilateral renal artery stenosis - This is a well-established clinical contraindication to prevent renal failure
Question 8: Beta2-agonists cause all except:
- A. Hyperkalemia (Correct Answer)
- B. Hyperglycemia
- C. Tremor
- D. Palpitation
Explanation: ***Hyperkalemia*** - Beta2-agonists actually cause **hypokalemia**, not hyperkalemia, by promoting the intracellular shift of potassium. - This effect is due to the stimulation of the **Na+/K+-ATPase pump** by beta-2 adrenergic receptors. *Hyperglycemia* - Beta2-agonists can lead to **hyperglycemia** by promoting glycogenolysis and gluconeogenesis in the liver. - They also decrease **insulin secretion** and increase insulin resistance. *Tremor* - **Tremor** is a common side effect of beta2-agonists, particularly in the hands, due to direct stimulation of beta2 receptors on skeletal muscle. - This muscle stimulation leads to increased muscle twitching and a fine tremor. *Palpitation* - **Palpitations** can occur due to the systemic absorption of beta2-agonists, leading to activation of beta1 receptors in the heart. - This can cause **tachycardia** and a sensation of a racing heart.
Question 9: Which of the following is not an adverse effect of chronic amiodarone therapy?
- A. Hypothyroidism
- B. Pulmonary Fibrosis
- C. Systemic lupus erythematosus (Correct Answer)
- D. Hyperthyroidism
Explanation: ***Systemic lupus erythematosus*** - Amiodarone is not typically associated with inducing or exacerbating **systemic lupus erythematosus** (SLE). - SLE is an **autoimmune disease** with a distinct set of symptoms and serological markers, rarely linked to amiodarone. *Pulmonary Fibrosis* - **Pulmonary fibrosis** is a well-known, potentially severe adverse effect of chronic amiodarone therapy, occurring due to drug accumulation in lung tissue. - Patients may present with **dyspnea, cough**, and diffuse interstitial infiltrates on chest imaging. *Hypothyroidism* - Amiodarone contains **iodine**, and its metabolites can inhibit thyroid hormone synthesis and release, leading to **hypothyroidism**. - This is a common endocrine side effect, often requiring **thyroid hormone replacement**. *Hyperthyroidism* - Amiodarone can also cause **hyperthyroidism** through two main mechanisms: an iodine-induced type (Type 1) or a destructive thyroiditis (Type 2). - Both types lead to excessive thyroid hormone levels and distinct clinical presentations.
Question 10: A 65-year-old woman with Parkinson’s disease has been experiencing worsening tremors despite taking levodopa. Which medication can be added to her treatment regimen?
- A. Phenytoin
- B. Aspirin
- C. Ropinirole (Correct Answer)
- D. Gabapentin
Explanation: ***Ropinirole*** - **Ropinirole** is a **dopamine agonist** that directly stimulates dopamine receptors (D2 and D3) in the brain, mimicking the effects of dopamine. It is commonly used as an **adjunct to levodopa** to improve motor symptoms and reduce off-time in Parkinson's disease. - When levodopa alone is insufficient to control symptoms (as in this case), dopamine agonists like ropinirole can help to prolong the therapeutic effects and manage **motor fluctuations**, including tremors, by providing more continuous dopaminergic stimulation. - Ropinirole is FDA-approved for both **monotherapy** in early Parkinson's and as **add-on therapy** in advanced disease with motor complications. *Phenytoin* - **Phenytoin** is an **antieconvulsant** medication primarily used to treat epilepsy and certain types of seizures. - It has **no established role** in the treatment of Parkinson's disease or its associated tremors. *Aspirin* - **Aspirin** is an **NSAID** and antiplatelet agent, commonly used for pain relief, fever reduction, and cardiovascular protection. - It does **not have direct therapeutic effects** on the motor symptoms of Parkinson's disease like tremors. *Gabapentin* - **Gabapentin** is an anticonvulsant and neuropathic pain medication, often used to treat **neuropathic pain**, restless legs syndrome, and seizures. - It is **not effective** for managing the tremors or other motor symptoms of Parkinson's disease.
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